STUDY OF MUTAGENICITY OF VIRAL VECTOR IN TUMOR GENETHERAPY

Objective: To observe the mutagenicity of retrovirus and adenovirus as transgenic vectors to evaluate the safety of transgenic tumor cells as tumor vaccines. Methods: Cells were cultured together with the virus. Then DNA and supernatant were tested for mutagenicity by means of genetic toxicological laboratory technique. Results: The results indicated that DNA and supernatant of transgenic cells had no mutagenicity through both in vivo and in vitro tests. Conclusion: The modified virus had no mutagenicity as a transgenic vector.

The big bang of genome editing technology: development and application of the CRISPR/Cas9 system in disease animal models

Targeted genome editing technology has been widely used in biomedical studies. The CRISPR- associated RNA-guided endonuclease Cas9 has become a versatile genome editing tool. The CRISPR/Cas9 system is useful for studying gene function through efficient knock-out, knock-in or chromatin modification of the targeted gene loci in various cell types and organisms. It can be applied in a number of fields, such as genetic breeding, disease treatment and gene functional investigation In this review, we introduce the most recent developments and applications, the challenges, and future directions of Cas9 in generating disease animal model. Derived from the CRISPR adaptive immune system of bacteria, the development trend of Cas9 will inevitably fuel the vital applications from basic research to biotechnology and bio- medicine.

基因转染间充质干细胞的临床治疗:特点与问题

背景:骨髓间充质干细胞因制备较易、具备有较强的自我增殖能力、稳定的生物学性状、低免疫原性、能在宿主脑中生存较长时间、易于转染外源性基因且有较高的转染率、对肿瘤细胞具有趋向性而成为一种较有希望的基因治疗的靶细胞。目的:利用不同基因转移的方法分析间充质干细胞用于临床多种难治性疾病基因治疗的优势和缺陷。方法:应用计算机检索2000年1月至2013年12月PubMed数据库、中国期刊全文数据库、万方数据库相关间充质干细胞的文章,中文检索词为"间充质干细胞,基因治疗",英文检索词为"mesenchymal stem cells,gene therapy"。共检索到文献2 114篇,最终纳入符合标准的42篇文献。结果与结论:基因治疗有多种,按基因操作分为:①基因修正和基因置换。②基因增强和基因失活。按靶细胞分为生殖细胞基因治疗和体细胞基因治疗。按给药途径分为活体外途径和活体内途径。相对与其他细胞骨髓间充质干细胞能在宿主脑中生存较长时间、易于转染外源性基因且有较高的转染率、对肿瘤细胞具有趋向性而成为一种较有希望的基因治疗的靶细胞。间充质干细胞作为基因治疗的载体其移植物抗宿主病、克隆氏病的治疗在国外已经进入到3期临床阶段。国内应用间充质干细胞治疗临床上一些难治性疾病也取得了明显的疗效。探索干细胞移植最佳治疗窗口,寻找适宜的基因剂量、移植细胞数量及合适的治疗时机,发挥最佳的治疗效果是有待解决的问题。

Cytopathic effects and local immune responses in repeated neoadjuvant HSV-tk+ ganciclovir gene therapy for prostate cancer

Objective:Cytopathic effects and local immune response were analyzed histologically in prostatic cancer(PCa)with in situ herpes simplex virus-thymidine kinase(HSV-tk)/ganciclovir(GCV)gene therapy(GT).Methods:Four high-risk PCa patients who received HSV-tk/GCV GT were investigated.After two cycles of intraprostatic injection of HSV-tk and administration of GCV,radical prostatectomy was performed.Formalin-fixed,paraffin-embedded sections were evaluated using immunohistochemistry.PCa with hormone therapy(HT,n=3)or without neoadjuvant therapy(NT,n=4)that were equivalent in terms of risk were also examined as reference.Immunoreactively-positive cells were counted in at least three areas in cancer tissue.Labeling indices(LI)were calculated as percentage values.Results:ssDNA LI in GT increased,indicating apoptosis,as well as tumor-infiltrating lymphocytes and CD68-positive macrophages,compared with their biopsies.GT cases showed significantly higher numbers of single-stranded DNA(ssDNA)LI,CD4/CD8-positive T cells and CD68-positive macrophages including M1/M2 macrophages than HT or NT cases.However,there was no significant difference in CD20-positive B cells among the types of case.There were strong correlations between CD8+T cells and CD68+macrophages(ρ=0.656,p<0.0001)as well as CD4+T cells and CD20+B cells(ρ=0.644,p<0.0001)in PCa with GT.Conclusions:Enhanced cytopathic effect and local immune response might be indicated in PCa patients with HSV-tk/GCV gene therapy.

GENETICALLY MODIFIED DENDRITIC CELLS INDUCED SPECIFIC CYTOTOXITY AGAINST HUMAN HCC CELLS IN VITRO

Objective: to transduce the tumor associated antigen gene MAGE-1 and/or IL-12 gene into dendritic cells (DC) and to observe the in vitro cytotoxic effect induced by the genetically modified DC against the human hepatocellular carcinoma (HCC) cell line SMMC7721. Methods: the MAGE-1 gene was inserted into the retrovirus vector LXSN to construct the recombinant retrovirus LMSN. The monocyte-derived DCs were transfected at appropriate differentiation stage by LMSN and/or a recombinant adenovirus AdmiL-12, which containing murine IL-12 gene. The control groups included retrovirus LXSN transfected, adenovirus AdBGFP transfected and non-transfected DCs. The MAGE-1 gene expression was identified by western blot and the mIL-12 p70 secretion was detected by ELISA assay. The in vitro cytotoxicities against SMMC7721 induced by genetically modified and control groups of DC were tested by MTT assay. Results: The MAGE-1 expression was detected by a monoclonal antibody in DCs tranfected with LMSN but not in control groups. At 16 h, 24 h and 48 h after transfection with AdmIL-12, the concentration of the mIL-12 p70 in the culture medium was 580pg/106 cells, 960pg/106 cells and 1100pg/106 cells respectively. The mIL-12 p70 secretions were not detected in other groups. The lytic activity (as judged by % lysis) induced by each groups of DC was 94.2±5.2% (LMSN and AdmIL-12 cotransfected group), 78.9±3.6% (LMSN transfected groups), 52.6±9.7% (AdmIL-12 transfected group), 34.7±4.3% (LXSN transfected group), 36.3±3.8% (AdBGFP transfected group) and 3.9±2.0% (non-transfected group) respectively. Except for LXSN transfected and AdBGFP transfected group, the difference of the lytic activities between other groups were statistically significant (P<0.05). Conclusion: The MAGE-1 gene modified DCs can induce relatively specific cytotoxicty against SMMC7721 in vitro and thus suggested that those genetically engineered DCs have the potential to serve as novel vaccine for HCC. Transduction of exogenous IL-12 gene into DCs may further enhance DCs’ activity and the effectiveness of the above DC vaccine.

Combination Adenovirus-Mediated HSV-tk/GCV and Antisense IGF-1 Gene Therapy for Rat Glioma

Objective To investigate the effects of combination adenovirusmediated HSVtk/GCV system and antisense IGF1 gene therapy for rat glioma and analyze the mechanism.Methods Using the recombinant adenovirus vector,GCV killing effeciency after combined gene transfer of HSVtk and antisense IGF1 was observed in vitro.Rat glioma was treated with HSVtk/GCV and antisense IGF1 and the survival rate of rats was observed.Results C6 cells transfected with tk and antisense IGF1 gene were more sensitive to GCV than that transfected with tk gene alone.The survival of the combination gene therapy group was prolonged significantly and large amounts of CD+ 4,CD+ 8 lymphocytes were detected in the tumor tissues.Conclusion Antisense IGF1 gene may enhance the tumorkilling effects of HSVtk/GCV.